Aggression- Neural And Hormonal Influences

Question 1

What are the two neural influences

Answer 1

The limbic system

The hippocampus

Question 2

What are two key structures in the limbic system that are associated with aggression

Answer 2

The amygdala

The hippocampus

Question 3

What is the limbic system

Answer 3

an area of the brain that helps to coordinate behaviours that satisfy motivational and emotional urges

Question 4

What is the amygdala responsible for

Answer 4

quickly evaluating the emotional importance of sensory information and prompting an appropriate response

Question 5

What happens if certain areas of the amygdala are simulated electrically

Answer 5

an animal responds with aggression such as snarling and adopting an aggressive posture

Question 6

What happens if certain areas of the amygdala are surgically removed

Answer 6

the animal no longer responds to stimuli that would have previously led to rage

Question 7

Who looks at if certain areas of the amygdala are surgically removed

Answer 7

Kluver and Bucy 1937 discovered that the destruction of the amygdala in a monkey who was dominant in a social group caused it to lose its domination place in the group

Question 8

What does Kluver and Bucy 1937 discover

Answer 8

The destruction of the amygdala in a monkey who was dominant in a social group caused it to lose its domination place in the group

Question 9

What is the hippocampus involved in

Answer 9

Formation of long-term memories and so allows an animal to compare the conditions of a current threat with similar past experiences

Question 10

What does an impaired hippocampal function prevent

Answer 10

The nervous system from putting things into a relevant and meaningful context and so may cause the amygdala to respond inappropriately to sensory stimuli resulting in aggressive behaviour

Question 11

What did Boccardi 2010 find

Answer 11

That habitually violent offenders exhibited abnormalities of hippocampal functioning

Question 12

What does serotonin do in normal levels

Answer 12

exerts a calming inhibitory effect on neuronal firing in the brain, it typically inhibits the firing of the amygdala the part which controls fear, anger and other emotional responses

Question 13

What does serotonin do in low levels

Answer 13

remove the inhibitory effect with the consequence that individuals are less able to control aggressive behaviour - serotonin deficiency hypothesis
Also associated with an increased susceptibility to impulsive behaviour aggression and even violent suicide

Question 14

what does the serotonin deficiency hypothesis result in

Answer 14

when the amygdala is simulated by external events it becomes more active causing the person to act on their impulses and making aggression more likely

Question 15

How does serotonin reduce aggression

Answer 15

By inhibiting responses to emotional stimuli that might otherwise lead to an aggressive response

Question 16

What does Mann et al 1990 do

Answer 16

Gave 35 healthy participants dexfenfluramine using a questionnaire to assess hostility and aggression levels they found that this in males was associated with an increase in hostility and aggression scores

Question 17

What is dexfenfluramine known as

Answer 17

deplete serotonin

Question 18

Name a hormonal influences

Answer 18

Testosterone

Question 19

What is testosterone

Answer 19

produces male characteristics one of which is aggressive behaviour and is said to peak in young males and then decline

Question 20

Who looked at testosterone

Answer 20

Sapolsky 1998
Dabbs et al 1987
Carre and Olmstead 2015

Question 21

What did Sapolsky 1998 do?

Answer 21

How removing the source of testosterone in different species typically resulted in much lower levels of aggression
Subsequently reinstating normal testosterone levels with injections of synthetic testosterone led to a return in aggressive behaviour

Question 22

What did Dabbs et al 1987 do and find?

Answer 22

Measured salivary testosterone in violent and non-violent criminals
Found that those with higher testosterone had a history of primarily violent crimes whereas those with lower levels only had committed non-violent crimes

Question 23

What did Carre and Olmstead 2015 do?

Answer 23

claimed that testosterone concentrations are not static but fluctuate rapidly in changes in social environment.

Question 24

What do all the studies show for testosterone?

Answer 24

Changes in test levels appear to influence aggressive behaviour by increasing amygdala reactivity during the processing of social threat.

Question 25

What evidence is there for the role of the amygdala in aggression

Answer 25

Pardini et al (2014)

Question 26

What did Pardini et al (2014) find?

Answer 26

The participants with lower amygdala volumes exhibited higher levels of aggression and violence
So reduced amygdala volume can predict the development of severe and persistent aggression

Question 27

What did Pardini et al (2014) do?

Answer 27

longitudinal male participants from child to adult

Participants with varying histories of violence were subjected to an MRI at age 26

Question 28

Who looked at evidence for the role of the hippocampus in aggression?

Answer 28

Raine et al 2004

Question 29

What did Raine et al do?

Answer 29

studies 2 groups of violent criminal those who faced conviction (unsuccessful) and those who evaded the law
MRI Scans

Question 30

What did Raine find

Answer 30

asymmetries in the hippocampus in the unsuccessful group the hippocampus in either hemisphere differed in size, an imbalance presumed to have arisen early in brain development

Question 31

What did researchers suggest the asymmetry found in Raine’s study

Answer 31

might impair the ability of the hippocampus and the amygdala to work together so that emotional information is not processed correctly leading to inappropriate verbal and physical responses as a result

Question 32

give two ways in which you would evaluate hormonal influences

Answer 32

inconsistence in evidence

aggression or dominance

Question 33

Explain inconsistency in evidence to evaluate hormonal influences

Answer 33

studies such as Albert et al 1994 + Olweus 1988 found a positive relationship between test + self reported and likelyhood of responding aggressively to provocation aggression however no correlation was found between test levels and actual violent behaviour among inmates in prisons suggesting relationship between test and aggression in humans is unclear

Question 34

Who looked at aggression or dominance as a way to evaluate hormonal influences

Answer 34

Mazur 1985

Question 35

What did Mazur 1985 suggest

Answer 35

we should distinguish aggression from dominance and aggression is one form of dominant behaviour lading to support the idea that rather than directly increasing aggression testosterone promotes statue seeking behaviour of which aggression is a type

Question 36

What is the difference between acting aggressively and acting dominated said by Mazur 1985

Answer 36

someone acts aggressively with the intent to inflict injury whereas someone acts dominantly to maintain status or achieve status

Question 37

Who gives research support for the serotonin deficiency hypothesis

Answer 37

Duke et al 2013

Question 38

What did Duke et al 2013 do?

Answer 38

Meta-analysis of 175 studies involving 6500 participants

Question 39

What did Duke et al 2013 find?

Answer 39

A small inverse relationship between serotonin levels and aggression, anger and hostility
The magnitude of the relationship varied with the methods used to assess serotonin functioning with year of publication and with self-reported versus other-reported aggression.
Only other- reported aggression was positively correlated to serotonin functioning

Question 40

What does Duke et al 2013 studies suggest?

Answer 40

the relationship between serotonin and aggression is more complex than originally thought

Question 41

Who looked at support for the serotonin deficiency hypothesis in non-humans ?

Answer 41

Raleigh et al 1991

Question 42

What did Raleigh et al 1991 find?

Answer 42

Vervet monkeys fed on experimental diets high in tryptophan exhibited decreased levels of aggression
individuals fed on diets that were low in tryptophan exhibited increased aggressive behaviour

Question 43

What did Raleigh et al 1991 results suggest ?

Answer 43

the difference in aggression could be attributed to their serotonin levels

Question 44

In Raleigh et al 1991 study what does tryptophan do ?

Answer 44

increases serotonin levels in the brain